It’s the other way round actually. On iOS you can install an adblock ruleset provider that Safari can use natively. On Android it’s only VPN or an adblock-enabled browser (that is usually yet another set of issues) because Chrome is adblock’s enemy. At least that’s my experience after long research while using both OS (recently, mid '20-21).
Properly configured, you can get much better adblocking capabilities on an Android phone than you can on iOS.
There's a weird situation with mobile phones where for most people who aren't going to go out of their way to make their devices private, Apple's ecosystem is the right choice; it has better defaults and better sandboxing. But once you do decide to go out of your way to make your device private, Apple's ecosystem stops being the right choice.
On a rooted Android phone I have network-level adblocking on my device that directly works with the firewall. I also run Ublock Origin in my phone browser, which blows every single Safari adblocker out of the water. I can also cut off Internet access to specific apps and games, not just to domains. I also have access to a litany of Open Source apps that wouldn't be allowed on app stores like NewPipe that improve my privacy by replacing services. And LineageOS imposes additional sandboxing on top of Android's built-in features.
But if a friend buys a phone, they're not going to do any of that. They can't get NewPipe because they're not using F-Droid. They're probably going to stick with Chrome, which has next to no adblocking or extra privacy controls. An iPhone will be more private and more secure for them in almost every way.
So it's a weird situation where which device is more private depends a lot on who you are. For most average consumers, it's likely iOS. But it's not quite so simple to say that iOS has the best privacy overall.
For network level blocking on Android there's no need to root or go down any rabbit holes. Just set your DNS to a adblocking service like nextdns. It's natively available since Android 9 and there are workarounds for older versions (usually by using an app that pretends to be a VPN).
You can do DNS based adblocking on Android as well using the built in "private DNS" support in combination with something like NextDNS. Doesnt need a VPN or special browser.
I don't know about Chrome adblocking because I'm using Firefox on all my Android devices. I installed uBlock Origin and I'm using it to block elements with CSS rules (lots of annoying sticky headers and useless navigation bars.) Sometimes I use it to block scripts. My primary adblocker is Blockada which is a local VPN and blocks all ads in all apps. This means that usually no ads make their way to Firefox and I remove their empty spaces from pages with uBlock.
The shortcoming of using Blockada is that I can't use another VPN. I don't really need it yet, but if I would that could be a big problem.
I don't know why Google doesn't allow chaining VPNs. Maybe the UX would be too difficult on a phone, maybe it's a real edge case not worth spending money on, maybe it would be used only to block ads.
If you want both: a blokada-like adblocker and a VPN, setting one up with Algo and WireGuard is quite easy. I've been using it for ages and it just works without me needing to interfere.
